China National Offshore Oil Corporation (CNOOC) announced on March 25 that it has discovered a high-yield oil and gas well in a formation over 5,000 meters deep in the Bohai Sea. The test yielded approximately 1,400 cubic meters of oil and gas equivalent per day, setting a new record for daily output from a deep-sea oil and gas exploration well in China.

The well is located in the central Bohai Sea, close to the Bozhong Sag, the largest hydrocarbon-rich depression in the Bohai Sea. The structure is a volcanic reservoir. The daily production of crude oil is 855 cubic meters and natural gas exceeds 500,000 cubic meters, equivalent to an oil and gas equivalent of about 1400 cubic meters., the exploration prospects are broad.

图为“海洋石油946”钻井平台正在进行钻探作业。 (中 国海油 供图)

Zhou Jiaxiong, Deputy General Manager of CNOOC Tianjin Branch, said that in China's offshore oil and gas exploration practice, strata with a depth of more than 4,500 meters are usually referred to as ultra-deep strata. The deployed prospecting well is buried in a submarine mountain more than 5,000 meters deep, with a formation temperature exceeding 180 degrees Celsius and a pressure exceeding 70 megapascals. It is a rare high-temperature, high-pressure ultra-deep oil and gas well in China, and completing drilling and obtaining high yield is indeed not easy.

The Bohai volcanic rocks' submarine hills are widely distributed, and the exploration is extremely difficult. Over the years, there have been no breakthroughs, and it is regarded as an exploration "no-go zone" in the traditional sense.

In recent years, CNOOC researchers have explored and proposed the theory of deep oil and gas exploration in extension-strike-slip composite fault zones, successfully predicted high-quality reservoir development areas in the Bohai volcanic buried hills, and explored high-yield oil and gas wells. Previously, under the guidance of this theory, several deep 100 million-ton oil fields such as Bozhong 26-6 and Bozhong 13-2 were discovered one after another.

Xu Changgui, deputy chief engineer of CNOOC Exploration, said that the successful drilling of this well has opened up a new field of offshore ultra-deep oil and gas exploration, effectively confirming the exploration potential of hidden buried hills in the Bohai Sea, and is of positive significance to accelerating the deep-ultra-deep exploration process in the Bohai Sea and building a trillion-square atmosphere at sea. (Wang Enbo)

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